Solder Paste Inspection Implementation.ppt

solderpasteinspectionwithse-300:asayieldimprovementstrategy,preparedby:stanleychendate:11aug2005,16-dec-19,2,flextronicscorporatepresentation,objective,todefineasetofguidelinesforimplementationofse-300solderpasteinspectionequipmentinordertoimprovethefirstpassyield.theguidelinescovers:a.thecausesforpasteheightvariationb.determinationofcontrollimitandtarget,16-dec-19,3,flextronicscorporatepresentation,applicationsofusingse-300,measurementofdimensionalcharacteristicsofsolderpastedepositssuchasheightandvolume2.printedpasteregistrationandbridgingcheck,16-dec-19,4,flextronicscorporatepresentation,variablesaffectingsolderpastedeposit,awiderangeofvariablesaffectsthesolderpastevolumedeposits.someofthemajorvariablesincludestencilaperturedesignprintingparameter(speed,pressure,separationspeed)printertooling(squeege,supportblock)solderpastecharacteristics(viscosity,tackiness)boardwarpage(especiallyafterreflow),16-dec-19,5,flextronicscorporatepresentation,stencilaperturedesigninfluence,thevolumeofsolderpasteappliedtoboardismainlyinfluencedbystencilaperturesizeandstencilthicknesstheabilityofpastetoreleasefromtheinnerwallsofaperturetoboardpadsdependsprimarilyonthreefactors:areaandaspectratioaperturesidewallgeometryaperturewallfinish,16-dec-19,6,flextronicscorporatepresentation,areaandaspectratio,ageneraldesignguideforacceptablepastereleaseis:(ipc7525)aspectratio1.5arearatio0.66(forbga,csp,0402,0201),16-dec-19,7,flextronicscorporatepresentation,aperturedesignguidelines,16-dec-19,8,flextronicscorporatepresentation,conclusionfromaperturedesigndifferences(ipc7525),1.volumeandheightofsolderpastedepositsaredeterminedbyaperturedesignandstencilthickness.differentcomponentswillhavedifferentpasteheight.thus,thereshouldbedifferentprocessspecificationofsolderpasteheightfordifferentcomponents.2.differentstencilthicknesscanbeusedforthesamecomponenttype,egbga(pitch=1.0mm,4.55.3milstencilcanbeused)bga(pitch=0.5mm,3.04.0milstencilcanbeused)qfp(pitch=0.5mm,5.06.0milstencilcanbeused)qfp(pitch=0.65mm,6.07.0milstencilcanbeused),16-dec-19,9,flextronicscorporatepresentation,printingparameterinfluence,adoewascarriedtodeterminetheeffectofprintingparameteronsolderpasteheight.,16-dec-19,10,flextronicscorporatepresentation,printingparameterinfluence,16-dec-19,11,flextronicscorporatepresentation,printingparameterinfluenceonpasteheight,16-dec-19,12,flextronicscorporatepresentation,printingparameterinfluenceonpasteheight,16-dec-19,13,flextronicscorporatepresentation,conclusiononprintingparameterinfluence,forindiumsolderpaste(nc-smq92j),themainprintingfactorthatwillinfluencethepasteheightis“separationspeed”thesolderpasteisquiteinsensitivetopressureandspeed(withinacertainrange)themeanof6.67milinpasteheightisonthehighersideofspecificationlimit(57mil)thepasteheightiscalculatedpercomponent(averageoftotalpads)theprintingiscarriedoutinbareboard,16-dec-19,14,flextronicscorporatepresentation,solderpasteprintingdoe#2,itwasobservedthatduringthefirstdoe,thewrongsupportblockisused.anseconddoeiscarriedtoseeifadifferentresultinpasteheightwillbeobtained.pasteheightondifferentcomponentswillbestudied3factors(pressure,speed,separation)andtwolevelsareusedtodeterminethepasteheight,16-dec-19,15,flextronicscorporatepresentation,solderpasteprintingdoe#2,2nddoewasdonebyusingthecorrectsupportblockandtodeterminethepasteheightvariationbetweendifferentcomponenttype,16-dec-19,16,flextronicscorporatepresentation,multiplemeasurementsofpasteheightperpad,16-dec-19,17,flextronicscorporatepresentation,solderpasteprintingdoe#2,16-dec-19,18,flextronicscorporatepresentation,solderpasteprintingdoe#2,16-dec-19,19,flextronicscorporatepresentation,solderpasteprintingdoe#2,16-dec-19,20,flextronicscorporatepresentation,solderpasteprintingdoe#2,16-dec-19,21,flextronicscorporatepresentation,conclusion:pasteprintingdoe#2,byusingthecorrectsupportblock,thesolderpasteheightbecomeslowerascomparedto1stdoeresults.basedonthedoeresults,the57milspecificationistootightandwillresultintoomanyfalsecalldifferentcomponentswillhavedifferentpasteheightthepasteheightiscalculatedasanaverageofallpcbpadsofacomponent.,16-dec-19,22,flextronicscorporatepresentation,boardwarpage,itwasobservedthattheboardwarpagecanhaveaneffectontherepeatabilitysolderpasteheighttheamountofboardwarpagecanbemorethan0.5mm,16-dec-19,23,flextronicscorporatepresentation,repeatabilityofspi(se-300),theaccuracyofse-300forheightis1015%oftargettherepeatabilityofse-300dependsontheamountofwarpagebetweenboard-to-boardbecausese-300usesthereferencescantodeterminethebaseline,16-dec-19,24,flextronicscorporatepresentation,stepstoimplementspi(suggested),defineobjectiveofusingspi,identifydefects,determinetargetandrange,monitoryieldafterrelfow,adjusttarget&rangebasedonyield,checkifrangeisappropriate,16-dec-19,25,flextronicscorporatepresentation,objectiveofusingse-300spi,toincreasefirstpassyieldbyreducingprintingdefectssolderingdefectsrelatedtopasteprintingprocessincludeinsufficientsolderbridging100%checkonallpads,16-dec-19,26,flextronicscorporatepresentation,determinationofprocessspecification,twoapprocahescanbeapplied:differentcontrollimitsbasedoncomponenttypesamecontrollimitstoaccommodateallcomponenttypes(thisalsoimpliesalargercontrollimitisrequired)-preferred,16-dec-19,27,flextronicscorporatepresentation,determinationoftargetandrange,theappropriaterangeisonethatminimizesescape(defectverifiedafterreflow)falsecall(adefectcallbyse-300thatdoesnotresultinpost-reflowdefect)therangeistocoverallcomponenttype(oralmost)therangeshouldalsoconsiderspiequipmentrepeatability,boardwarpage,andotherprocess/productionvariations.,16-dec-19,28,flextronicscorporatepresentation,determinationoftargetandrange,basedonthecomponenttype,thefollowingstencilcanbeused(asrecommendedinipc7525)fortheappropriatesoldervolumeandheightbga1.0mmpitch(u42000)=4.55.3milstencil(arearatio=0.780.67)ubga0.8mmpitch(u12000)=3.04.0milstencil(arearatio=0.920.69)0402(r8035)=46milstencil(arearatio=1.00.65)thethinnerstencilrepresentsthesuggestedminimumsolderpasteheightthatwillproducegoodsolderjoint.thethickerstencilrepresentsthelimitthatthepastecanreleasefromaperturewithoutanyproblem.however,thisdoesnotmeanifthepasteishigher,itwillresultindefectsafterreflow,16-dec-19,29,flextronicscorporatepresentation,determinationoftargetandrange,usingstln6207modelasanexample(5milstencilused),thefollowingstepsareusedtocreatedprocessspecificationstep1:asastart,usethenominalstencilthicknessasthetarget.inthiscase,thetargetwillbe5mil.step2:determinethelowerprocessspecificationchoosethelowerspecbasedonipc7525fordifferentcomponent(asastartingreference).inthiscase,theminimumsolderpasteheightshouldbe4.5milreducethelowerspecfurthertoaccommodatedifferentaperturedesignandprocessvariation.thustheinitial4.5milreducedto4.0mil.thisrepresentsa20%tolerancefromthetarget.forsomelargeaperture(i.e,j81700),itissuggestedtosetat3.5milaslowerlimit,16-dec-19,30,flextronicscorporatepresentation,determinationoftargetandrange,step2(continued):determineupperprocessspecification.theupperlimitisreachedwhenthepossibilityofsoldershortishigh.asastart,theindustrypracticeof50%fromthetargetisapplied.thus,theuppercontrollimitisat7.5mil.step3:checkifrangeisappropriatemultiplemeasurementsaretakentodeterminethe“potential”fallcalls.suggestedthereportederrorsshouldbelessthan10.step4:monitorthefirstpassyieldafterreflowdeterminethefypandidentifyanysolderingdefectsduetoprinting.step5:ifopenisfound,thenincreasethelowercontrollimit.ontheotherhand,ifsolderbridgingisdetected,thenreducetheuppercontrollimit.,16-dec-19,31,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,25measurementsonasinglepadaretakentodetermineiftherange(6sigma)isappropriate.thereported“errors”byse-300issuggestedtobecontrolledatlessthan10(pads).,16-dec-19,32,flextronicscorporatepresentation,multiplemeasurementsofpasteheightperpad,16-dec-19,33,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,34,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,35,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,36,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,37,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,38,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,39,flextronicscorporatepresentation,multiplemeasurementsofpasteheight,16-dec-19,40,flextronicscorporatepresentation,firstpassyieldafterreflow,remark:nosolderingdefectsduetoprinting,16-dec-19,41,flextronicscorporatepresentation,pasteheightcontrollimit:padvscomponent,se-300isabletomeasurethepasteheightforeverypcbpad.however,wiandspccontrolthepasteheightonapercomponentbasis.whenthepasteheightiscalculatedonapercomponentbasis,itisdonebyaveragingouttheindividualreadingofallpcbpadsofacomponent.theaveragepasteheightofacomponentishigherthanthatoftheindividualpcbpad.,16-dec-19,42,flextronicscorporatepresentation,pasteheightcomparison:padvscomponent,16-dec-19,43,flextronicscorporatepresentation,finalconclusion,basedonthestudyofstln6207-famodel,thefollowingconclusionsaredrawn:pasteheightwillvaryduetoaperturedesign(arearatio)fordifferentcomponent(whileholdingothervariablesconstant).theheightvariationisnotnecessaryanindicationofprocessvariation.whenthearearatioisveryhigh(eg,j81700),thepasteheighttendstobelower.ontheotherhand,whenarearatioisnear0.66,theshapeofpastedepositstendstobelikepyramidshape(insteadofflattopshape),andtheaverageheighttendstobehigher.3.thelowestpasteheightonapad(3.73mil)isonj81700,whilethehighestpateheight(6.3